Proposal to look for an up/down asymmetry in atmospheric neutrinos beyond the multi-GeV region with existing experimental data

Abstract

We discuss a possible test of the neutrino oscillation hypothesis by proposing a combined analysis of high energy atmospheric neutrino induced muon events that have been detected around the horizontal direction in the Kolar Gold Field (KGF) underground site and below the horizontal direction by many large detectors such as Super-Kamiokande and MACRO. The up/down asymmetry obtained using contained events recorded by the detectors at the Kamioka site probes the low energy region of the atmospheric neutrino whereas the suggested method probes high energy neutrinos. It mainly depends on the observations and it is free of uncertainties in the neutrino flux, the interaction cross section, etc. Here we demonstrate that the method is sensitive to the region of oscillation parameter space that explains all the features of the atmospheric neutrino data in the Super-Kamiokande detector, the limiting factor being the statistical strength of the KGF observations. This method provides the only way to study the up/down asymmetry beyond the multi-GeV region which is yet to be measured experimentally.